The plaza surface-and-drainage infrastructure is designed to function as a large self-sustaining cistern. Water from rainfall and snow melt is channeled into large holding tanks and re-used to support the Memorial forest via a specialized drip-and-spray irrigation system.

The Memorial grove is a dense planting of trees--a forest at the heart of the redeveloped World Trade Center. As they grow the trees will provide shaded space to increase comfort for visitors and reduce heat absorption on the plaza. The transpiration of the many leaves will cool the air throughout the district.

The plaza is designed with a network of maintenance tunnels that provide access to site systems--irrigation, electrical, drainage. These tunnels will extend the life of the plaza by allowing maintenance crews to access, test, adjust, and repair systems with ease.

Substantial soil volumes, adequately irrigated, aerated, and drained, are the most critical element in the long-term success of the Memorial grove. An enormous volume of soil--40,000 tons in total—lies buried beneath the plaza to ensure that the oaks will grow and thrive to maturity.

The stone paving is set in place using sand instead of a rigid mortar. When repairs are required, the stone can be removed undamaged and re-set in sand again. There will be no need for quarrying additional stone in the future.